By MIKE STOBBEA federal panel is recommending that older people vaccinated for shingles get a new, better shot approved in October. The advisory panel said the vaccine made by GlaxoSmithKline works better than the first one made by Merck, which has been sold in the U.S. since 2006. Health officials say many as 20 million Americans should get a second round. Shingles, a painful blistery condition, occurs when the chickenpox virus resurfaces later in life. Merck's vaccine is recommended for people 60 and older. But health officials say its effectiveness drops sharply after about five years. The Advisory Committee on Immunization Practices said doctors should first opt for Glaxo's Shingrix, licensed last week, which uses a new ingredient to boost its effectiveness. It was recommended for people 50 and older.